A gunman behind the gang-linked execution of a South End drug dealer was sentenced to 15 1/2 years in prison on Friday.

Jallah Drake, 22, also known as "La" and "La-Boo," additionally received five years' post-release supervision from Judge Stephen Herrick for the Nov. 29, 2011 shooting of Richard "50 Cent" Gibbs.

Gibbs, 25, was on his way to meet friends for a late-night snack when he was killed in a retaliation hit about 1 a.m. near Fourth Avenue and Clinton Street. He was pronounced dead on arrival at Albany Medical Center Hospital.

Drake pleaded guilty to first-degree manslaughter last month. He and three codefendants, all of whom already pleaded guilty to misdemeanor weapon charges, were identified as members of the Yard Boys street gang based in the city's Ida Yarbrough housing development. Gibbs was a drug dealer for the Original Gangsta Killas street gang, known as OGK. The two gangs were at odds.

The series of events behind the slaying began when one of Drake's future codefendants, Jahmeek "Meeker" Croley, was shot at the Ida Yarbrough complex on Nov. 28, 2011, according to people with knowledge of the case. In response, Drake and his codefendants went into the South End on Nov. 29, 2011; Drake shot Gibbs, who was never identified as Croley's shooter.

Then on Dec. 2, 2011, codefendant Kareem "G.B." Collier was shot in the Ida Yarbrough complex, which prompted Drake, Croley and a third accomplice to seek retaliation. They were charged with gun possession after they tossed a pistol, authorities said.

Authorities highlighted Gibbs' gang connections after a March 2012 sweep by state Attorney General Eric Schneiderman's office. They said Gibbs would have been charged in that case had he survived.

Drake's case was prosecuted by Chief Assistant District Attorney David Rossi.